{
 "id": "AIR-2025-0305",
 "slug": "cve-2025-53366-mcp-python-sdk-fastmcp-server-denial-of-servi",
 "title": "CVE-2025-53366: MCP Python SDK FastMCP Server Denial of Service Vulnerability",
 "summary": "A validation error within the FastMCP server component triggers unhandled exceptions upon processing malformed requests. This results in repeated server errors and service unavailability until restarted.",
 "type": "attack_on_ai",
 "categories": [
  "infra_vuln"
 ],
 "severity": 2,
 "targets": [
  "framework_or_tooling"
 ],
 "products": [
  "mcp",
  "fastmcp server"
 ],
 "incident_date": "2025-07-04",
 "incident_date_precision": "day",
 "first_reported": "2025-07-04",
 "sources": [
  {
   "url": "https://github.com/advisories/GHSA-3qhf-m339-9g5v",
   "publisher": "GitHub Advisory Database",
   "title": "CVE-2025-53366: MCP Python SDK vulnerability in the FastMCP Server causes validation error, leading to DoS",
   "published_at": "2025-07-04"
  },
  {
   "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-53366",
   "publisher": "NVD",
   "title": "CVE-2025-53366: The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP).",
   "published_at": "2025-07-04"
  }
 ],
 "source_count": 2,
 "confidence": 0.95,
 "status": "published",
 "origin": "seed_ghsa",
 "tags": [
  "CVE-2025-53366",
  "mcp",
  "dos"
 ],
 "created_at": "2026-10-18T07:00:14.101Z",
 "updated_at": "2026-10-18T10:04:21.885Z"
}